sex

Introduction

sex, term used to refer both to the two groups distinguished as males and females, and to the anatomical and physiological characteristics associated with maleness and femaleness. Sex relates to the type of reproduction in which specialized reproductive cells (gametes) form and, when united by fertilization, produce a zygote (fertilized egg) that develops into a new individual. The female gamete is called an egg or ovum, and the male gamete a sperm.